There Has to Be an Easier Way: Facet Fracture Characteristics That Reliably Differentiate AOSpine F1 and F2 Injuries

To identify morphologic features of isolated cervical spine facet fractures that can reliably differentiate AOSpine F1 and F2 injuries. Retrospective review of cervical spine CTs on all patients who sustained isolated cervical fractures of the facets presenting to our level 1 trauma center from August 2012 through December 2015. CTs were reviewed for facet fracture characteristics and AOSpine facet fracture classification. Association between facet fracture characteristics and AOSpine classification was assessed through multivariable logistic regression models. Fifty-six patients with cervical spine fractures isolated to the facets were included in the study. The mean age was 36 (range 9–90) years with 55.4% (n = 31) males. A significant correlation was found between subtype F1 and subtype F2 in laterality (left- or right-sided) (p = 0.004), interfacetal fracture involvement (p < 0.0001), transverse process involvement (p < 0.001), displacement of fracture fragment (p < 0.001), comminution of fracture (p < 0.0001), and vertebral arch disruption (p = 0.001). After multivariable analysis, left side laterality (p = 0.03), transverse process involvement (p = 0.01), and fracture comminution (p = 0.003) were associated with F2 fractures. Facet fractures with transverse process involvement or comminution have a higher probability of being an F2 fracture. These characteristics may be helpful when categorizing facet fractures using the AOSpine classification.